East Flower Garden Bank

Bathymetric map of East Flower Garden Bank showing the sanctuary boundary, as well as other relevant management zones and infrastructure.
East Flower Garden Bank is located about 13 miles east of West Flower Garden Bank. Credit: FGBNMS

Depth Range: 62-446 feet (19-136 meters)

Distance from Land: 119 miles (192 km)

Area: 28 square miles (73 sq km)

East Flower Garden Bank is a pear-shaped bank located 119 miles (192 km) south of the Texas/Louisiana border and approximately 13 miles east of West Flower Garden Bank. This is one of the two original banks that made up the sanctuary when it was first designated in 1992.

The original boundary for East Flower Garden Bank closely followed the outer edges of the BOEM No-Activity zone, but was later expanded to incorporate additional hard bottom features along the outer edges of the bank.

Coral Reefs

East and West Flower Garden Banks are best known for the beautiful coral reefs located on the shallowest areas of each bank. These are the northernmost coral reefs in the Gulf of Mexico, thriving at the northern limits of coral survival.

These are also the healthiest coral reefs in the greater Caribbean/Gulf region with over 52% coral cover, which is as much as 5 times the amount of hard coral as other reefs in the region. The corals have literally piled up on one another over thousands of years, creating high profile reefs that rise 15-20 feet (4.6-6.1 meters) above the nearest sand patches in some areas.

The dominant species here are brain and star corals, many of which are considered threatened species (OrbicellaI annularis, Orbicella faveolata, Orbicella franksi). These threatened species account for about 60% of the coral cover at East Flower Garden Bank.

Coral reef with purple fish swimming above it
Large brain and star corals dominate the coral reef at East Flower Garden Bank. Photo: G.P. Schmahl/FGBNMS
A large brain coral eroded into a mushroom shape with a fringe of leafy green algae at its base
Erosion from waves, urchins, and other reef grazers has carved some corals into interesting shapes. Photo: G.P. Schmahl/FGBNMS
An area of reef covered in small branching corals with purple rope sponges poking up in between
Large patches of small branching corals (Madracis auretenra) are found in some parts of the reef at East Flower Garden Bank. Photo: G.P. Schmahl/FGBNMS

While the coral reef is the most-well known part of East Flower Garden Bank, there are several other notable features in this part of the sanctuary.

HI-A-389-A Platform

When the sanctuary was designated in 1992 there was a single operating gas production platform, High Island A-389-A (HI-A-389-A), located one mile southeast of the reef cap. In 2018, the upper portion of the platform was removed and the rest remains in place as an artificial reef.

Sanctuary research vessel moored on a buoy with a gas platform in the distance

The HI-A-389-A platform was located one mile from the reef at East Flower Garden Bank (where the sanctuary research vessel is moored). Photo: FGBNMS

Brine Seep

Another unique feature of East Flower Garden Bank is a brine seep, where super salty water (over 200 ppt) is seeping out from the salt dome under the bank. This water is very dense, allowing it to settle beneath normal sea water (35 ppt) and form an underwater pool up to 10 inches deep.

Map showing the location of the brine seep at East Flower Garden Bank.
The brine seep and the associated brine pool are located on the southeast side of East Flower Garden Bank at about 240 feet (73 meters).

The density difference is so distinct, you can see what looks like a puddle even though it’s already underwater. Nothing but bacterial mats survive in this brine seep. Fish swim over it, but can’t live in it.

What looks like a puddle of water leaving a white deposit on nearby rocks
The salty water seeping up from the salt dome beneath the bank is much denser than the surrounding seawater and settles to the bottom, forming what looks like a puddle. Photo: Sea Research Foundation and Ocean Exploration Trust
A brown fish swimming over white bacterial mats on the sea floor
This marbled grouper is swimming just above the brine seep pool and the bacterial mats that live there. Photo: Sea Research Foundation and Ocean Exploration Trust
A blurry image of a trunkfish swimming overhead
The density difference between the brine seep water and the surrounding seawater creates a blurry layer where the two meet, making it hard to see this smooth trunkfish swimming overhead. Photo: FGBNMS/UNCW-UVP

Mesophotic Reefs

Below the reef cap lie deeper mesophotic habitats such as algal reefs, algal nodule zones, and deep coral zones that include populations of black corals and octocorals.

Feathery branches of a white coral hang over rocky habitat.
Some deep corals are rooted in the midst of algal nodule zones, rocky-looking areas created by crustose forms of algae. Photo: FGBNMS/UNCW-UVP
Pink fish swim past wiry orange corals on a deep reef.
A school of threadnose bass (Choranthias tenuis) swims through deep reef habitat at East Flower Garden Bank. Photo: FGBNMS/UNCW-UVP
Orange and white striped fish next to deepwater corals.
Black corals and octocorals provide habitat for a variety of reef fish like this deepwater squirrelfish (Sargocentron bullisi). Photo: FGBNMS/UNCW-UVP